Sagiv Moran, Goldhammer Ehud, Ben-Sira David, Amir Ruthie
Sports Medicine and Rehabilitation Division, Zinman College of Physical Education and Sport Sciences, Wingate, Israel.
Gerontology. 2007;53(6):357-61. doi: 10.1159/000104898. Epub 2007 Jul 3.
Aging-related changes occur mainly in the cardiopulmonary system and skeletal muscles, bringing about a reduction in physical performance. Consequently, maximal oxygen uptake (VO(2)max) decreases.
The current study investigated exercise oxygen utilization during maximal aerobic exercise in trained and untrained elderly.
Fifteen trained (59.3 +/- 1.1 years) and 15 untrained (60.1 +/- 1.1 years) elderly underwent a peak cardiopulmonary exercise test on a bicycle ergometer. Arterial O(2 )was defined from echocardiograph and venous oxygen content.
At rest, trained compared to untrained elderly had significantly (p < 0.05) higher values of end diastolic volume (108.1 +/- 5.8 and 100.7 +/- 6.2 ml, respectively) and stroke volume (68.1 +/- 4.3 and 57.3 +/- 6.5 ml, respectively), while heart rate (68.7 +/- 9.3 and 81.3 +/- 8.2 beats . min(-1), respectively), and mean arterial blood pressure (90.6 +/- 6.9 and 95.4 +/- 7.2 mm Hg, respectively) were significantly lower. At peak aerobic test, the trained elderly, compared to the untrained subjects, achieved significantly (p < 0.05) higher values of end diastolic volume (156.1 +/- 8.2 and 134.1 +/- 7.6 ml, respectively), stroke volume (123.0 +/- 7.9 and 96.0 +/- 4.8 ml, respectively), cardiac output (20.2 +/- 1.5 and 15.0 +/- 1.3 liters.min(-1), respectively) and oxygen uptake (42.1 +/- 2.1 and 31.1 +/- 2.4 ml.kg(-1).min(-1), respectively), while diastolic blood pressure (70.3 +/- 5.6 and 77.5 +/- 4.2 mm Hg, respectively) and total peripheral resistance [4.3 +/- 0.8 and 5.9 +/- 1.41 (dyn.s(-1).cm(-5)).10(-1), respectively], were significantly (p < 0.05) lower.
The present study suggests that the differences between trained and untrained elderly in absolute oxygen uptake of the working muscles and peak power output at maximal exercise test are due to physical activity status. The higher aerobic capacity in the trained elderly is related to increased cardiovascular function and to a lesser extent to increased muscle mitochondria concentration and capillarity. Although untrained elderly have reduced maximal oxygen uptake at peak aerobic exercise, intrinsic regulation of mitochondrial function does not seem to be significantly altered because of aging associated physical inactivity. Therefore, untrained elderly can partially compensate for their lower cardiac output by increasing oxygen extraction to levels comparable with those of trained elderly.
与衰老相关的变化主要发生在心肺系统和骨骼肌，导致身体机能下降。因此，最大摄氧量（VO₂max）降低。
本研究调查了受过训练和未受过训练的老年人在最大有氧运动期间的运动氧利用情况。
15名受过训练的老年人（59.3±1.1岁）和15名未受过训练的老年人（60.1±1.1岁）在自行车测力计上进行了心肺运动峰值测试。通过超声心动图和静脉血氧含量测定动脉血氧。
静息时，受过训练的老年人与未受过训练的老年人相比，舒张末期容积（分别为108.1±5.8和100.7±6.2毫升）和每搏输出量（分别为68.1±4.3和57.3±6.5毫升）显著更高（p<0.05），而心率（分别为68.7±9.3和81.3±8.2次/分钟）和平均动脉血压（分别为90.6±6.9和95.4±7.2毫米汞柱）显著更低。在有氧测试峰值时，与未受过训练的受试者相比，受过训练的老年人舒张末期容积（分别为156.1±8.2和134.1±7.6毫升）、每搏输出量（分别为123.0±7.9和96.0±4.8毫升）、心输出量（分别为20.2±1.5和15.0±1.3升/分钟）和摄氧量（分别为42.1±2.1和31.1±2.4毫升/千克·分钟）显著更高（p<0.05），而舒张压（分别为70.3±5.6和77.5±4.2毫米汞柱）和总外周阻力[分别为4.3±0.8和5.9±1.41（达因·秒⁻¹·厘米⁻⁵）·10⁻¹]显著更低（p<0.05）。
本研究表明，受过训练和未受过训练的老年人在工作肌肉的绝对摄氧量和最大运动测试时的峰值功率输出方面存在差异，这是由于身体活动状态所致。受过训练的老年人较高的有氧能力与心血管功能增强有关，在较小程度上与肌肉线粒体浓度和毛细血管密度增加有关。尽管未受过训练的老年人在有氧运动峰值时最大摄氧量降低，但由于与衰老相关的身体不活动，线粒体功能的内在调节似乎并未显著改变。因此，未受过训练的老年人可以通过将氧摄取增加到与受过训练的老年人相当的水平来部分补偿其较低的心输出量。
